Ground Effect

And suddenly the down force just went off the clock and it was like hang on a minute, we’ve discovered something here. They didn’t quite know what it was. And Mario famously “the Type 78, well, I’ll tell you it is like it’s painted to the road.” When ground effect arrived, team Lotus had an unfair advantage. Maximum down force, minimum drag was what designers kind of went to bed dreaming of and it proved to be the winning ingredient.

Ground effect is actually a term that’s used on airplanes and it’s in relation to the buoyancy that a wing experiences when it gets near to the ground. Team Lotus had a reputation for innovation and a reputation for working harder than any other team, even when they were winning, they were always there until midnight and beyond. And that was very much driven by my father. He was always looking forward and if he gained an advantage, he’d be thinking how can I gain more advantage?

Ground effects came about from a root and branch review that my father undertook of formula one car design. And he got a clean sheet of paper, went back to basics. The 29 page dossier was delivered to the Team Lotus engineers, including Tony Rudd and Peter Wright and various aspects of design were considered, in particular aerodynamics. Peter Wright was charged with that aspect and was sent off to Imperial College Wind Tunnel and the end result was ground effect and step change in Formula 1 design.

So Peter was working on his aerofoil shaped sidepods and almost by accident noticed that towards the end of the day when everything was getting a little bit hot, the glue in the plasticine holding this rather rudimentary model together as the aerodynamic sidepods sank to the floor of the wind tunnel, suddenly the down force seemed to go up. And they couldn’t quite work out what was going on. And then they were trying to hold the sidepods up with little bits of wire and that didn’t work terribly well.

And then they actually put some bits of card along the edge of the sidepods which went all the way down to the floor of the wind tunnel and suddenly the down force just went off the clock and it was like hang on a minute, we’ve discovered something here. They didn’t quite know what it was.

What’s happening with a racing car is more to do with the Bernoulli principle. When fluid flows through a constriction it has to speed up and there’s a consequent reduction in pressure. The most vital part of ground effects in racing cars is the skirts. The air passing through this restriction has to speed up. The pressure drops and the all-important side skirts acting as a seal between the high-pressure air outside the car and the low-pressure air under the car, then suddenly you’ve got a lot of low pressure under the car for very little drag hence the big increase in performance.

So the skirts were key and to begin with the skirts on the type 78 weren’t that effective. But my father and Peter Wright realized skirts were the key and they just kept going until they got it right. Halfway through the season they came up with the parallelogram skirt system with ceramic rubbing strips on the bottom, suddenly it started working and they found a second lap just like that. And from then on the type 78 and then the much more sophisticated type 79, Team Lotus had a massive advantage.

For the drivers ground effect really was everything they ever wanted. Lots of down force, lots of grip with very little drag so they were still flat out down the straits and they came to the corners and they could go significantly quicker. When the team went with Gunnar Nilsson to Snetterton, the local circuit for the first time with the 78 with the skirts which really worked, Gunnar came back to the pits and his eyes were out on stalks and said “God, this is fantastic!” He was a second lap quicker and he said “I’m a meter from the curb.” You know, he wasn’t even trying. It was just night and day. And Mario famously “The type 78, well, I’ll tell you, it’s like it’s painted to the road.”

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